Sealing arrangement in a plug-and-socket coupling with a pressure fluid passage, particularly between the spout of a liquid gas container and a discharge regulator mounted thereon
This application is a continuation of application Ser. No. 190,411, filed May 5, 1988, now abandoned. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a sealing arrangement in a two-part plug-and-socket coupling with a pressure fluid passage, particularly between the spout of a liquid gas container and a discharge regulator mounted thereon. A first coupling part accommodates a valve to be opened upon assembling of the coupling, a second part is provided with a protrusion to be inserted into the inlet of the pressure fluid passage of the first coupling part, and an annular gasket is provided in one of the coupling parts. 
     BACKGROUND OF THE INVENTION 
     In an arrangement of said type, used e.g. in connection with portable liquid gas containers, the pressure fluid passage of the container spout, i.e. of the first coupling part, discharges through a bore, the diameter of which is only a little larger than the diameter of the portrusion of the second coupling part. An O-ring is provided to perform sealing around the protrusion in the assembled state of the coupling. For this purpose, it is a condition that the O-ring fits tightly around the protrusion. The O-ring will, thus, be exposed to a certain wear any time the protrusion is forced into and is pulled clear of the mouth of the container spout. The higher the fluid pressure which the O-ring is to seal against, the tighter the O-ring must fit about the protrusion, since the pressurized fluid seeks to leak through the joint between the annular gasket and the protrusion. 
     SUMMARY OF THE INVENTION 
     The sealing arrangement according to the invention differs from the prior embodiment in that the annular gasket is axially displaceable within an annular chamber that is provided in the second coupling part between the protrusion and a surrounding skirt and which is open in the direction towards the first coupling part. The annular gasket is in close abutment on the internal surface of the skirt while access for the pressure fluid is provided between the gasket and the protrusion to the annular chamber behind the gasket. 
     In this case, the annular gasket may be spaced from the protrusion of the second coupling part. Thus, prior to the eventual assembling of the coupling, it may have only a slight pressure against the internal surface of the skirt, thereby almost completely preventing it from being exposed to mechanical wear. This is due to the fact that the sealing effect of the annular gasket after the coupling parts have been joined depends on the circumstance that the pressure fluid leaking out around the protrusion inserted into the mouth will be caught in the annular chamber behind the annular gasket. This annular gasket is thereby urged firmly against the internal surface of the skirt as well as against the end surface around the mouth of the fluid flow passage of the first coupling part. This causes the annular gasket to effectively obstruct the joint left between the skirt and the end surface and which constitutes the only possible leakage way of the pressure fluid. When disassembling the coupling parts, the annular gasket will again be relieved of the fluid pressure responsible for the obstructing effect so that no considerable wear will occur in this phase. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a preferred embodiment of the invention by showing the components, relevant in the present context, of the discharge spout of a liquid gas container and a discharge regulator while being mounted, but not yet completely tightened up, and 
     FIG. 2 is a part of FIG. 1 on a larger scale and with the components to the left of the illustration in the same situation as in FIG. 1, while the components to the right are shown after the regulator has been fully tightened up. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The drawing illustrates the top portion 1 of a spout representing the plug or first part 40 of a plug-and-socket coupling 30 and disposed to be firmly stuck in a portable liquid gas container (not shown). This first port 40 in an ordinary way is provided with an external circumferential groove 2 and a channel or flow passage 3 accommodating a self-closing valve member (not shown) provided with a control spindle 4. At its top, the passage has a narrowed outlet in the form of a bore 5. 
     An associated regulator 6 which represents the socket or second part 50 of the coupling and may accommodate a diaphragm-operated reduction valve (not shown) includes an annular collar 7 adapted to be pushed down over the top of the spout 1 and supposed to be provided with locking means, for instance balls or hooks, for engagement with the annular groove 2 of the container spout. Such a locking arrangement is known in various forms and is, therefore, not shown in the drawing. 
     The regulator or control device 6 includes, moreover, a central stud or protrusion 8 which with a suitably small clearance may be received in bore 5 of spout 1 and which itself has a bore 9 establishing a connection between the passage 3 of the spout and a discharge channel 10 with a filter in the regulator 6. In a manner also known, the bore 9 accommodates a displaceable valve opener 11 that is spring-biassed in the upward direction and which may be pressed downwards against the spring force by means of an eccentric cam 12 at the end of a manually operated shaft 13. 
     The regulator 6 also has a skirt 14 encircling the stud 8 and defining together therewith a downwardly open annular chamber 15. The radial width of the chamber 15 is somewhat larger than the cross-sectional diameter of the annual gasket 16. Gasket 16 is illustrated as an O-ring, but it may as well have another cross-sectional shape which in its mounting position abuts slidingly against the internal surface of the skirt 14 the lower edge of which, in this position, is located at some distance above the top surface 17 of spout 1. The annular gasket 16 is squeezed into the annular chamber 15 through the somewhat narrowed slit between the lower edge of the skirt 14 and a shoulder 18 formed on the stud 8 and against which the gasket is urged by a spring 19. Spring 19 is illustrated as a bellows, but it may be of any other type as well. In the mounting position, the gasket 16 may thereby be kept clear of the top surface 17 of the spout, against which it abuts upon tightening up the regulator 6; see the right side of FIG. 2. 
     Between the annular gasket 16 and the stud 8, a narrow space 20 is left, see FIG. 2, which, after the valve member with the spindle 4 has been opened, allows pressure fluid that leaks out through the joint around the end of the stud 8 inserted into the bore, to penetrate into the annular chamber 15 behind the gasket 16. This urges said gasket outwardly towards the skirt as well as downwardly towards the top surface 17 so that the joint 21 between said components is effectively obstructed. Thus, preventing pressure fluid from leaking out this way. This also applies in case the skirt is not tightened up to abut firmly against the container spout, as supposed in FIG. 2. 
     Various modifications of the details illustrated in the drawings having already been mentioned above, but other modifications may obviously also be made. Instead of the self-closing valve member with the spindle 4, a manual valve may for instance be used so that the valve opener 11 becomes superfluous. This will particularly be the case in alternative applications of the sealing arrangement dealt with, e.g. in pneumatic systems or liquid conduits. Moreover, the pressure fluid access past the gasket 16 may be ensured in another way than shown, for instance by grooves in the gasket or in the stud.